The present invention relates generally to a heat exchanger having removable tube-and-fin assemblies, such as found in a diesel engine cooling system, and more particularly to a support for the tube-and-fin assemblies such that the overall strength and rigidity of the heat exchanger is enhanced.
A heat exchanger includes a multiplicity of tube-and-fin assemblies. The tube-and-fin assemblies are mounted in headers, arranged in columns and rows, and interconnected to receive and pass a heating/cooling fluid (dependent upon application).
In certain environments, the tube-and-fin assemblies must have considerable length in order to provide sufficient heat transfer. The rigidity of the assembly decreases with increased length, and thus it is often necessary in such applications to include a central header, in essence splitting the tube-and-fin assemblies. Utilization of a central header does, however, substantially reduce fin surface area, thereby reducing heat transfer capacity.
Each tube-and-fin assembly is removable from the headers for repair and/or replacement. One such assembly includes a generally elliptical tube having flat or flattened sides and a pair of heat-dispensing fins secured along the flat sides of the tube. In another type of assembly, the tube configuration is substantially circular in cross section. As is well known in the art, the fluid passes through the tube and heat therefrom is dispensed by the fins into the environment.
To ensure proper operation and sufficient heat transfer (e.g., cooling of the fluid in a radiator application and heating of the environment in a heat recovery application), it is desirable to maintain the spacing between tube-and-fin assemblies and to substantially control movement and/or vibration, without substantial forfeiture of fin surface area. On the one hand, movement and vibration of the tube-and-fin assemblies, as a result of operation or impact, can produce serious damage due to (i) excessive movement or deflection of individual assemblies, or (ii) contact between adjacent assemblies. Any loss of fin surface area, on the other hand, renders the heat exchanger less effective for a particular application.
It is possible to essentially band together the rows and/or columns of tube-and-fin assemblies and thereby increase the strength and rigidity of the heat exchanger. This, unfortunately, substantially inhibits the ready removal and repair or replacement of any single damaged assembly.
To avoid the repair problem, various "spacers" are now available. One such spacer is shown in U.S. Pat. No. 4,216,824, and the teachings thereof are incorporated herein by reference. One difficulty with this spacer and others presently available is that, with vibration, the spacer can dislodge or separate from the tube-and-fin assembly, thereby becoming ineffective. Further, the presently available spacers do not provide sufficient support in applications involving long tube-and-fin assemblies (e.g., in excess of forty inches in a typical vertical radiator application) or severe duty (e.g., an earth-moving vehicle) to eliminate the need for center headers.
More significantly, however, the presently available spacers and spacing mechanisms fail to accomplish the dual purpose of protecting the tube-and-fin assemblies from damage while maintaining the individuality of the assemblies. As such, the "trade-off" for protection is substantially increased difficulty in inspection, removal, and repair.